PhysX isn't Nvidia exclusive.Neither are all the others like FXAA.
They can all be used on AMD cards as well.You just need to enable it in the options.
Ill just leave this link here.
http://www.techspot.com/review/577-borderlands-2-performance/page5.html
And this
http://www.tomshardware.com/reviews/geforce-gtx-660-ti-memory-bandwidth-anti-aliasing,3283-12.html
And due to their higher bandwidth AMD cards perform better at higher resolutions and/or multiple monitors compared to their Nvidia competitors.
Usually that advantage isn't that big but there are games in which the extra bandwidth really helps.
http://www.techspot.com/review/591-medal-of-honor-warfighter-benchmarks/page4.html
The 660 Ti is also very overpriced compared to its AMD competitors.The HD 7870 is about as fast as the 660 Ti (+-10) and costs 60 dolars less on avarage.The HD 7950 is faster than the 660 Ti, more overclockable(when overclocked and overvolted becomes faster than a GTX 680), more future proof, features an incredible bundle and can be had for the same price as a 660 Ti.
In my opinion you should buy this card
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150605&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
Or this card (listed in benchmarks as HD 7950 Boost)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202006&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
Or, if you aren't going to overclock and want PhysX, the card below.
If you want an Nvidia card this is the only one that you should consider.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130787&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=